Understanding how behavior develops is an important challenge facing the developmental, behavioral, biological, and clinical sciences. Thus, the study of neurobehavioral development is essential because it fosters improvements in diagnostic tools, therapeutic interventions, and cures for developmental motor and neurological disorders. Recognizing that there are multiple determinants of behavior and that development is not a predetermined plan, this application aims to examine the contribution of sensorimotor experience during the perinatal period for two action patterns expressed by the developing rat. The first specific aim examines the effect of sensory feedback on the expression and development of locomotor-like stepping behavior in the newborn rat. Experiments will evaluate effects of restriction of the range of motion (ROM) and treadmill training on quipazine- induced stepping behavior. The second specific aim examines the effect of sensory modulation on the coordinated le.g.extension response (LER) in the newborn rat. Experiments will employ methods of ROM restriction, unilateral weighting, and motor training to determine real-time and lasting effects of cutaneous and proprioceptive feedback on the LER. The third specific aim examines the effect of normally-occurring, species-typical sensory stimulation on the development and plasticity of these behaviors. Experiments will manipulate maternal behavior to determine the role that maternal-infant interactions play in shaping the ontogeny of locomotor behavior and the LER. The findings from this project may provide implications for physiotherapies for human infants with motor and neurological disorders (e.g., cerebral palsy, spina bifida and muscular dystrophy). PUBLIC HEALTH RELEVANCE: This project will contribute to our understanding of neurobehavioral development by examining the sensory modulation of behavior patterns in the perinatal mammal. The findings from this project may provide implications for physiotherapies for human infants with motor or neurological disorders (e.g., cerebral palsy, spina bifida and muscular dystrophy) and individuals with spinal cord injuries.